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Hi. I'm rebuilding my ARC SP6. Almost done with the PS and line stages, now for the phono section.Has anyone here rebuilt the phono stage for an ARC preamp? Looking for pointers on caps and resistors to use. Thinking of PRP for the resistors, RTE for the small RIAA caps, and playing with Russian caps (have K40, K42, K72, K75, FT3 on hand), or Cardas, for the input and output caps.
But, would appreciate the sharing of any experiences and tips.
Follow Ups:
...state of the art modern circuit?Pretty pointless doing all that work, and spending good $$ on great parts, to only have what is basically a very slightly revamped 60's circuit - IMO.
Consider either my FVP5A circuit, one of Thorsten's (before he went to transformers everywhere) or the classic Arther Loesch design - all are similar in concept and any one of them will be sonically light years ahead of anything out of ARC - let alone the SP-6!
Hi Allen. I've decided to go with your FVP5A phono section. I just ordered a pair of the matched FETs from your site.Can you take a peek at the SP6 (not A,B, etc) schematics to see if you think I can hack it in there with the existing power supply etc. I think the heater is already elevated over 200v.
Thanks, Samir.
The SP-6 and other ARC 12AX7 based preamps have (IMO) insanely high B+ voltages and even higher pre-regulator voltages.My 6922 based circuits need FAR less B+, the FVP5A has a 250VDC B+.
So I suggest you do what I did when rebuilding a SP-8 - I inserted a choke before the first filtercap which made it a choke input filtered supply - which dropped the pre-regulated B+ down some30% so your510 etc becomes more like 360V which then is easy to regulate to the 250V needed.
> I think the heater is already elevated over 200v <
It is - but that's far too high if the B+ comes down to 250...
-----------------------------------------------IMO, it's not viable to use the ARC line stage and my phono as the B+ requirements are so different,
so I agree 100% with Stephen R that you should make one complete design and not try to mix them.He has provided links to schema's for a number of preamps - the same ones I also suggested - and any of them will make a SP-6, even one with great parts, sound sad, tired, slow and cloudy!
Do one of them right - don't mix them - OK?
Regards, Allen
My DIYery started with my own versions of SP3, 6, 8, 10. Must have built 20 or so all with primo parts at the time. However a modern phono kills them dead. They are old ideas and sound it. Things have moved on quite a bit since. Allen is right.Thorsten's version of the Arthur Loesch Design
There are loads more out there BUT if you're going to build from scratch and you aren't an experienced phono stage builder, then go for a complete design including power supply as these things can get problematic.
Can you point me to some links? Thanks
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